The proposed research will investigate the cognitive and neurological processes underlying language comprehension. Event-related brain potentials (ERPs) will be recorded while subjects read or listen to sentences containing specific deviations from well-formedness. Two approaches are taken in examining ERP effects associated with language comprehension. The first approach focuses on the ERP components themselves, in an attempt to learn more about the cognitive events underlying these effects. Recent work has indicated that syntactic and semantic anomaly elicit distinct ERP effects (the P600 and N400 effects, respectively). The proposed research investigates the hypothesis that these effects are elicited as a function of the linguistic level of the anomaly. The second approach focuses on the process of comprehension. How does the comprehender rapidly derive a single, coherent interpretation of the language input? How quickly are relevant types of information used, and which types of information have precedence over other types of information? The proposed research will use ERP responses to linguistic anomalies to investigate the use of information during language comprehension. Specifically, these experiments will examine the use of information in resolving ambiguity at the syntactic and coreferential levels of analysis. Finally, how similar are the processes that underlie the comprehension of written and spoken language? The proposed research will investigate this question by directly contrasting the ERP response to written and spoken sentences. Although the proposed experiments involve normal adult subjects, one long-term goal is to study language comprehension in children and adults with language disabilities (e.g., the dyslexias and aphasias). The studies proposed here, by furthering our knowledge concerning the cognitive and neural bases of comprehension in normal comprehenders, provide a critical starting point for subsequent ERP investigations of language pathologies.